Caissons for wharf construction and method of installing same



Jan. 3, 1961 CAISSONS FOR WrIARF' CDNSTRUCTION AND METHOD 0F' Filedsept. s, 1953 E. J. QUIRIN INSTALLING SAME 4 Sheets- Sheet 1 v 1 1 l 1 l1 l l l 1 l i l l I E 1 ii 11 11 11 Il I il IN VEN TOR.

Edward J QUI-fm E. J. QUlRlN Jan. 3, 1961 CAISSONS FOR WHARFCONSTRUCTION AND VMETHOD OF INSTALLING SAME 4 Sheets-Sheet 2 Filed Sept.8, 1953 INVENTOR.

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cAIssoNs FOR WHARF CONSTRUCTION AND METHOD oF INSTALLING SAME Jan. 3,1961 4 Sheets-Sheet 5 Filed Sept. 8, 1953 lllllllll Il |||l| S #www ON w.a f P hllll llll |.l \\\T\ N m fm ATTORNEY E. J. QUIRIN 2,966,778

cAIssoNs Foa` www CONSTRUCTION AND METHOD oF TNSTALLTNG SAME Jan. 3,1961 4 Sheets-Sheet 4 Filed Sept. 8, 1953 MMA ATTURNEK United StatesPatent CAISSONS FOR WHARF CONSTRUCTION AND METHOD OF INSTALLING SAMEEdward J. Quirin, Great Neck, N.Y., assignor to Frederic R. Harris,Inc., New York, N.Y.,'a corporation of New York Filed sept. s, '1953,ser. No. 318,816 7 claims. (c1. `6in-46) This invention is animprovement in waterfront installations; particularly structures to beerected along the shore of a body of water at chosen sites 'requiringwharves and the like, to facilitate loading and unloading marinevessels.

In localities where there is 'a great vdilerencebetween the water levelat high and low tide, serious diiculties are encountered in theconstruction and maintenance of bulkhead wharves alongside of whichships of large draft are to be moored. When, for example, sheet pilingis set up along the outer side of a wharf or dock and backed on the landside with earth or rocks, the pressure of the water at flood tide bracesthe piling and offsets to a large extent the outward horizontal thrustexerted by the weight of `any earth ll between the piling and the bankor shore. Such thrust tends to overturn the piling, especially at lowtide that is much below high water pressure is much diminished. Hencebulging and other distrotion and damage or wrecking of the wharf orpier, in whole or in part, may ensue.

A real problem must therefore be faced; and I have solved it by means ofa row of concrete caissons or cofferdams placed end to end to form arugged massive retaining wall `adjacent the waters edge, ballasted withstone or other heavy and bulky materials to withstand the pressure ofthe earth iill along the inshore side; while ensuring suicient draftalong the opposite or outer side. The Colfer-dams or caissons are Ibuiltby casting the concrete in shadow tidal basins, getting them afloat withone side under water, flooding them to swing the bottom down and thesides upright and at last moving them to the site; Where they aresettled upon a prepared bed at the proper depth under the water surface.The caissons or coffer-dams when finally in place are provided withports or openings for the inow and outflow of water as the tide risesand'falls and will advantageously bear the weight of the earth along theinshore sides, as AWell as support a suitable top layer to make levelareas or a platform for handling cargo.

The nature of the invention and other objects and advantages thereofwill appear as the detailed specification proceeds; and the novelcharacteristics are defined in the appended claims. The improvementcomprises both the structure employed and the method of erection, and isfully illustrated in the accompanying drawings. The disclosure, however,is explanatory only and minor alterations in construction and steps ofproceeding may be adopted without deviation from the general design orplan which. is embodied vin theinventiona On saiddrawings: f

Figure 1 isa top plan of forming a continuous wharf.

Figure 2 is a vertical cross section of a caisson according to thisinvention, in ultimate position, taken on line 2 2 of Figure 1.

Figure `3 is an elevation of-sad caisson viewed kfrom the right ofFigure 2.

part of aline of caissons tide, when the opposing l Y '2,966,778Patented Jan. 3, 1961 he 1C@ Figure 4 is a top plan of the `caisson ofFigure 3.

Figure 5 is a side view of a caisson under construction at a tidalbasin.

Figure 6 is a horizontal section of a detail.

Figures 7 to l1, inclusive, are cross sections of such a caisson invarious preliminary stages of the set-ting upI operation.

Figure 12 shows in perspective part of installation as it appears whencompleted; and

Figure 12a shows another detail.

As illustrated in Figure l, the body of the Wharf consists mainly ofseveral caissons or coier-dams arranged end to end along the line of ashore or bank 10. See Figures 2 and 12. The caissons all have closedbottoms and open tops. They are constructed on the. land near the site,floated, ooded with water to keep' their open tops uppermost, and movedto the site to be sunk upon the earth under the water; the submergedsoil having been previously prepared to receive them.

Each caisson has the over-all shape of an elongated box with closedbottom 1,`deep sides 2 and 3, and ends 4. The sides and ends arerespectively parallel to each other, with the ends `4 perpendicular tothe bottom, but the parallel sides 2 and 3 are canted or tilted in thesame direction, so that the angle they make with the bottom are eachdifferent from a right angle, as is made clear on Figures 2, 5, 7, 8, 9,l0 and 1l. The caissons thus lean backward, so to speak,. towards theshore and have greater stability; and-the stability is furtherincreased" by a long projecting toe or ledgeS along the outer side 2. atthe bottom 1.

, The interior of each caisson has a, full length" longitudinalpartition or bulkhead 6 standing midway of both; sides and parallelthereto; and transverse partitions lor bulkheads 7 reaching from oneside to the other, and parallel to the ends 4. These'par-titions allextend up from the bottom to .the top of the caisson and divide theinterior of the caisson into two long rows of compartments 8 `and 9.When the caissons have been sunk at the site and rest with the bottom 1on the earth under the water, the compartments are all loaded and filledwith rocks which act as ballast, holding the caissons upright andpreventing displacement, as long as the ground under them remains Ii'lrmenough to support their weight. The earth under the water at the site oferection is first scooped or dredged to present a shallow trench or bed11v near the shore line 10, as shown in Figures 2 and l2. The trenchreceives a layer of sand 12 and then is lled level with stone and gravel13. The partition 6 is parallel to the sides 2 and 3.

After the caissons have been correctly located end to end on this bed11, the sapec between the inshore sides 3 of the caissons and the bankor shore 10 is lled with stone 14, piled against the side 3 and othermaterialsA 1S back of the layer 14, till a level stretch of v'ground islobtained substantially flush with the tops `of the caissons; the heightof the sides 2 and 3 and the depth of sinking of the caissons beingcalculated in -advance to give this result. y Y

The caissons all have considerable len'gth and when several are disposedend to end at the site, a wharf or pier several hundred feet in lengthcan easily and quickly be constructed.4 The ballast inthe compartments8k and 9 enables the caissons to withstand the pressure of vwhatevermaterial is dumped in to fill the space between; the land and the sides3, land the ledges 5 along the bottom at the outer side 2 help to offsetsuch pressure. With the walls 2 and 3 slanted andthe caissons heavyenough, the ledegs 5 can be omitted.

Each caisson is creteaud built in a shallow tidal basin close to apreferably made of reinforced of water but separated from it by a dam ordike along the shore, and pumped out dry. When the basin is ooded laterthe caisson or coier-dam is floated out and towed to the chosen site inthe manner indicated on Figures 5 to l1 inclusive.

The caissons are cast by pouring concrete into molds put up in the tidalbasin 16 near the large body of water 17. The surface of the basin isexcavated to a required depth below the level at high tide of the water17, and protected by the dike or dam 18. This dike has couduits orllumes 19 running through it at the level of the door of the basin 16,and each conduit is controlled by a gate valve 20, so that the basin canbe flooded and drained at will. Each caisson is built in the basin withthe side 3 prone and the other side 2 above it; the bottom 1 beingslanted or tilted slightly and the ends 4 upright. When the bot-tom,sides and ends have set and hardened, the caisson will be as it appearsin Figure 5.

Each caisson needed in the operation is then equipped with temporarybulkheads, disposed parallel to the bottom, and located so as to closein part what will later be the open top of the structure. The temporarybulkheads are indicated at 2 1 and 22 and extend across the bulkheads 7and ends 4. The bulkheads 21 and 22 for each caisson are wide enough tocover most of the distance between the side 3 and long central bulkhead6, but terminate short of the bulkhead 6. Each bulkhead 21 consists ofseparate lengths or sections, arranged end to end and attached by boltsand nuts or other means in a leakproof manner to the edges of the sidesy3 and partitions 7.

The side .3 Of each caisson has internal ribs 23, and the bulkheads 7and ends 4 have internal ribs 24, and the bulkheads 21 and 22 aresecured to the ribs by bolts 25 and nuts 2 6. As indicated in Figure 6for the bulkheads 22 the ribs 23 and 24 are located well within the openends of the compartments 9, and for the bulkheads 21 the ribs are at theopen ends of the compartments; all ribs being of course parallel to thebottom 1. The temporary bulkheads 21 and 22 thus confine between thecross partition 7 a series of chambers 30, and these bulkheads 21 and 22carry valves 27 and 28, respectively, close to the side 3. Above eachchamber 30 thelong middle bulkhead 6 has manholes 29 in the middle .ofeach length between the bulkheads 7.

The bulkheads 21 and 22 can be provided with gaskets to be compressedagainst the ribs 23 and 24 and make a water tight t. When the caisson isto be floated, the valves 20 are opened; and the basin 16 is floodedwith water owing through the conduits 19. The valves 27 are opened inadvance, but the valves 28 in the bulkheads 22 are kept closed. Hencewater enters and rises in the chambers 30; and the weight of the waterin the chambers or tanks 30 holds the coier-dam in horizontal positionwith the side 2 and ledge 5 uppermost. The draft of the caisson is lessthan the depth of the water in the vbasin at high tide; and the caissoncan be towed into deeper water; after the dike 18 is breached; andrighted, preparatory to towing it to the site and sinking iton the bed11.

`Someof the transverse bulkheads 7 have ports or holes therein andothers are imperforate or without such holes or ports. The latter areVindicated at 7a and 7b, Figure 4. Each bulkhead 7a has a singlebulkhead7 between it and the adjacent lend 4. Hence the ends and sides-ofthe caisson and thebulkheads 7a enclose a group of four compartments8 and 9 at each end of each caisson; and the bulkhead 7 nearest to eachend has ports or openings 31 on each side of the central bulkhead 6,said ports being near the bottom 1. One of said ports in the bulkhead 7is near the side 3, and the other near the bulkhead 6 and between it andthe opposite side2. Thus the two compartments 9 of this group betweentheside; andbillkhead .21min Commusisatipn with each other and so arethe'other two compartments 8 of this group on the other side of thebulkhead 6. Therefore a single hose line, when the caisson is beingswung up or righted, can supply water to the two compartments of thisgroup, or conduct water out, as may be required. The hose is passed intothe caisson at the top.

The next imperforate bulkhead 7b without ports has sin compartmentsbetween it and rthe bulkhead 7a, and the two intervening transversebulkheads 7 have openings 3i in the same locations as in the bulkhead 7next to the end 4. Hence this group has three compartments 8 between theside 2 and bulkhead 6; and three other compartments 9 between the side 3and bulkhead 6 similarly connected; and these compartments 8 can also beooded or evacuated in unison. The total number of compart4 ments and thenumber in each group can be varied; but each caisson may contain ve;groups; between the side 2 and bulkhead I6, one group of twocompartments 8 at each end and three groups of three compartments eachbetween the groups at the ends 4, with the intermediate transverse.bulkheads allhaving openings 31 as above described.

While the building of the caisson is in progress, ladders and othersupports, mold forms, etc. are used, and a catwalk is put up along theedge of the middle bulkhead 6. Bits and cleats, not shown, for mooringand towing lines are attached where needed to the sides at the open endsof the compartments.

The basin is kept closed olf from the sea by the temporary dike 1S, andhas its iloorat the mean lower water level. The average rise of thetide, from mean low to mean high water, is, for example, approximately20 feet. Thus, with the flume gates 20 opened, it is possible to ood theconstruction basin with a depth of water to about 20 feet, when the tideis highest.'

When the completed caisson vis ready for a trial at oating, it is rstcleared of all dunnage (forms, scatfolds, debris, rain and curingwater), all holes 31 in the transverse bulkheads 7 are cleared ofobstructions. These holes are in all the transverse bulkheads, exceptthe four bulkheads 7a and 7b which separate the groups of thecompartments 8 and 9.

Two sets of draft gages, not s hown, are provided on each of theexterior faces of the ends of the caisson, to aid in determining thelist and trim las well ,as the draft of the caisson when this is afloat.The two sets are so arranged that they'will give normal draft readingswhen the water line is parallel to the sides Zand 3 orthe bottom 1, orthe caisson, respectively.

A depth gage, not shown, is installed in each yof the chambers 30. Thesegagesare set vertically andindicate the depth of water ballast in thetanks. Depth gages, not shown, are also instal-led in the compartments 8of the caisson between the side 3 and bulkhead 6, and four depth gages,not shown, which determine the depth ot water in the basin at thevarious stages oftide are installed near the four corners of thecaisson.

Two clinometers, also not shown, with a range, are installed, oneon'each of the two exterior faces of the ends of the caisson, at theupper corners near the side 2. The purpose of the clinometers is`toestablish the transverse list of the caisson when' it comes afloat andduring the careening or righting stage. Longitudinal trim can only beaccomplished after readings taken from thel draft gages.

The draft at which the caisson will oat freely and the amount of waterballastrequired to'avcid list and trim are estimated, but the actual,correct values 'of draft and amount of ballast can be determined 'onlywhentrialis made. The caisson can stay aoat within the ooded basin onlywhile the tide is at or near the high mark.

Therefore, the time available for the floating operation during one hightide period is limited. lf adjustments of the quantity of water ballastin the chambers 3 0 mustbe made in order to correct the list and trim ofthe caisson. there will not be sutlicient time for tlting and towing thecaisson out of the basin, all during one high tide. If, instead, thecorrect amount of ballast is pre-determined during a previous trial, thefloating operation will be expedited considerably.

At low tide, then the gates 20 in the dike urnes 19 are opened. Thevalves 28 in bulkhead 22 are closed, those in bulkhead 21 are o'pen.Thus, as the tide rises, the water level will rise equally Iandsimultaneously in the whole tidal basin 16 and water enters the ballastholds or chambers 30 of the caisson. During this time men on rafts arestationed at the four corners of the caisson so that they will be ableto read at intervals the caissons draft gages and the basins depthgages. Men, also on rafts, are stationed in the ballast tanks, to readthe ballast depth gages.

When the reported Water llevel in the ballast tanks or chambers 39reaches three-quarters (2%) or so of the estimated final level, thevalves 27 in the long bulkhead 21 are closed so that no more water willenter the ballast tanks 30. As the tide rises further, the water depthin the basin will gradually approach the level at which it is estimatedthat the caisson will be buoyed up fully. By this time all mooring linesmust be in place, but with areasonable amount of slack. At a certainmoment the lower horizontal side of the caisson will begin to rise fromthe oor of the basin; due to the fact that bottom and adjacent parts areheavier, the corner between the bottom 1 and side 2 will remain aground.More water isv now allowed to enter the ballast tanks 30 by opening andregulating the valves 27 in the bulkheads 21, so that the angle of list,read from the clinometers, will never exceed 1 to 2 degrees,corresponding to l to 2 feet difference in the readings of the draftgauges on the outside of the ends 3. Thus, when said corner is liftedfrom the oor of the basin, and the caisson is fully waterborne, thereshould be a small list or difference in draft between the parts of thecaisson at the left in Figure 5 and the parts along the bottom 1, of thecaisson, the latter being the lower. The reason for this list is thatthe amount of ballast water introduced so far in the tanks 30 is not yetsufcient to counterbalance completely the heavier weight of the bottomand adjacent parts. By close regulation of the valves 27 in the bulkhead21, enough additional water is then allowed to enter the tanks 30 so asto reduce the list. When the clinometer indicates 0 and the draftreadings are equal, the valves 2'7 and 28 are closed.

n Due to the shape and length of the caisson,there should not be anyappreciable list from one end,4 to the other end. However, draftheadings must be taken at both ends and, if they should indicate adifference greater than a few inches, the necessary adjustments in theballast will have to be made.

' With .the caisson floating evenly, the water depth in all the tanks 30and the outside draft are read accurately from the respective gages andare then recorded.

, As the tide recedes, the caisson will again come to rest on the basinfloor. However, if bulkheads 21 and 22 are reasonably leak-proof, thewater is retained in the tanks 30. This is done to avoid the necessityof re-gaging and re-adjusting that Water when the caisson is to be towedout of the basin. y

Next, the portion of the dike 18 to be used as outlet is breached, allthe way downto the basin floor level, during periods of low tide. Withthe basin open to the body of water 17,` thus the caisson willalternately float and settle with the variations of the tide, but, beingstill correctly ballasted, it will always maintain its horizontalposition. At the selected high tide, the caisson is towed out of thebasin lthrough the dikes breach and is moored in a convenient locationuntil all preparations for the careening or righting operations arecompleted. The pumping equipment required for righting operation is madeready on rafts. A site is selected where there are not less than about40 feet at low tide; and on a fairly calm day, the caisson is towed tothe site and moored there by its two ends, with plenty of room andsufficient slackv so as to permit the free rotation of the caissonduring careening. The rafts carrying the puipig equipment are mooredalong the length of the caisson, at the open ends of the compartments 8.Men are stationed, on the caisson, adjacent the manholes 29, throughwhich, by means of rods, they can operate the valves 28 on the innerbulkheads 22. Temporary scatfolds or platforms are erected on thecaisson to permit men to work safely at any angle within range coveredby the careening.

When everything is ready, the valves 28 on the bulkheads 22 are openedand the water in the chambers 30 is allowed to flow past these bulkheadstoward the bottom 1 of the caisson. Hence, the caisson will graduallyrotate about a longitudinal axis. See Figure 7. VIt is estimated that,with the valves 28 fully open, it will take over 1/2 hour to turn thecaisson through approximately 34.

In the succeeding phase the pumps are set in motion and, through hoses,water is pumped into the compartments 8 of the caisson between the side2 and bulkhead 6. The water must be introduced uniformly into the groupsof compartments 8 all along the length of the caisson, so that nolongitudinal list or strain in the structure of the caisson will becreated. Readings taken from the depth gages in the various compartments8 will be the guide and the water will be regulated accordingly. As thecompartments 8 of each group are in communi cation through the ports 31,only one hose line for each group of such compartments 8, or five linesin all, instead of a separate line for each requirement, is required.

The caisson thus swings successively through varying angles of tilt orlist, as shown by Figures 8 to l1 inclusive. All through the stage ofcareening or righting to put the bottom 1 under the water, theclinometers on the two end faces of the caisson are watched and willindicate when the operation is completed. The draft gauges, now verticalat the four corners of the caisson, will give equal readings. The waterin the compartments 9 along the side 3 will be somewhat deeper than inthe compartments 8 along the side 2.

The caisson can now be towed back to any convenient point and mooredwhile preparations are made for sinking it at the shore line 10.

a In preparation for sinking the caissons at the site of the wharf, acatwalk is constructed along 'the outer face of the side 2 at the top,another along the face of the bulkhead 6 at the top, and several alongthe tops of the bulkheads 7. These catwalks need not be shown. Thebulkhead 21 also serves as a working platform above the side 3. Thecaisson are towed to the shore line 10 and submerged so that they standon the bed 11 with the bottoms 1 perfectly horizontal. Several trialswith each casson may be necessary, water being pumped in and out of thecompartments 8 and 9 to lift and settle the caisson till correctposition is attained. During this stage outside water can ow freethrough the caissons from the outer side 2 to the inboard side 3 throughducts 32, built into the transverse bulkheads 7, just below the low tidelevel, the ends of these ducts in the sides 2 and 3 being open. Thus thewater is maintained at the same level along the side 2 and 3 during thesettling operation, and disturbance of the stability of the caissons isprevented. i

When the sinking of the caissons has been satisfactorily performed bypumping water into the compartments 8 and 9 to the required depth, holes33 in two horizontal rows are opened in the bulkhead 6, two in eachhorizontal row of holes being between each twol adjacent bulkheads 7.These holes are formed in place' o when the caissons are built but arekept closed by plugs` 34. The upper row of holes 33 are just below thehigh water level and the lower row just under low tide level adjacentthe conduit 32. These holes are opened at low tide by men in boats or onrafts who knockout the plugs 34. The upper and lower holes are matchedby laeejrs upper and I ower holes 35 andtat the same levels in the sides2 and ,3, which are alsoopened by removing vthe same kind of plugs 34.The water can now rlse and fall the tide in all the caissons, which arethen lld tram bottom to the tops .with rock b allast.37 in the com.-partments 8 and 9, and the till 14 and ,15 is heaped in between theshore and the side 3. ,A coping wall 38 is cast along the top of theside 2 and earth is laid on the caissons and fill to makea smoothtopsurface. Y.

The adjacent ends of the caissons have vertical flanges 3 9. approachingeach other and the space 4Q between said ends is filled with rocks likethe rocks 1 4. To iinish the wharf, vertical fenders 41 are attachedtothe outer wall2 of each caisson by b olts embedded in theconcrete. Thefenders are all in line with the bulkheads 7, and to 'each fender nearthe top a steel cable 42 is atiixed. The lower ends of Athese cables areanchored to concrete block s k44 in the bed 11. Along the front of eachcaisson runs a floating fender 45 of wooden beams, with sleeves 43through which the cables pass. The fenders are free to rise and fallwith the tide but are kept in place at the water line by the cables 42.`At the opposite ends of the entire wharf, the caissons have verticalbeams 46 and 47, the former secured to the end danges 39, and thesebeams are joined by horizontal wales 48extending from the top down tolowtide level to protect the ends of the wharf against vessels, bargesortlighters that might bump against the ends.

Having described my invention, what I believe to be new 1s: yl. Acaisson havingclosed bottom, sides and ends and an open top, a centrallongitudinal bulkhead extending between the ends, and transversebulkheads extending be,- tween the sides and intersecting thelongitudinal bulkhead, said transverse bulkheads andthe longitudinalbulkhead dividing the .interior of the caisson into compartments betweensaid longitudinal bulkhead and said sides, some of saidtransversebulkheads being imperforate and having one or more of theother transverse bulkheads and `a group of saidcompartments between themand sealing the compartments of said group from the remainingcompartments, the transverse bulkheadsbetween said imperforate bulkheadshaving openings putting all the compartments of veach group` onhone sideofthecntral bulkhead into communication with one another; said openingsbeing adjacent aside of thecaisson for the compartments between thecentral bulkhead and said side, and adjacent the central bulkhead forthe remaining convv partments of the group between the central bulkheadand the opposite side. v2. A caisson having closed bottom, sides andendsand an open top, a central longitudinal bulkhead extendlbetween theends, andtransverse bulkheads extending between the sides andintersectngthe longitudinal bulkhead, said transverse bulkheads .andthelongitudinal bulkhead `dividing the interior of thecaisson intocompartments between said longitudinal bulkhead and saidsides, Some ofsaid transversebulkheads being imperforate and having one or more of theothertransverse bulkheads anda group ofsaid compartments between themand sealing the compartments of said groupl from the remairiingcompartments, the transverse bulkheads/ between said imperforatebulkheadshaving openings putting all the compartments of each group oneone sideoflhe centrai bdlkhead into communication with one anothensaidopenings being adjacent a side of the caisson for thecompartrnents.between the central bulkhead and said side, and adjacent the centralbulkhead for the remaining oo mpartments of the group between thecentral bulkhead and lthe opposite side, the transverse bulkheadscarrying ducts that are parallel to the bottom and pass through thelongitu-v dinal bulkhead, said ducts having both ends open in the sidesof the yc aSS'Q'if 3; A caisson having closed bottom, sides and ends andan open Atop,` a central longitudinal bulkhead ex- 8 tending betweentlie ends, an d transverse bulkheads en' vtetidingbetween the sides andintersecting the longitudinal bulkhead, said transverse bulkheads andthe longitudinal bulkhead dividing the interior of `thercaisson intocompartments between said longitudinal bulkhead and said sides, some ofsaid transverse bulkheadsbeing impe'rf forate and having one or more ofthe other transverse bulkheads and a group of said compartments betweenthem and s ealingthe compartments yof said group from the remainingcompartments, thetransverse bulkheads between said imperforate bulkheadshaving openings putting allthe compartments of each group one one sideof the central bulkhead into communication with oneanother, saidopenings being adjacent a side of the caisson for the 4compartmentsbetween the central bulkhead and said side, and adjacent the centralbulkhead for the remainingcompartments of the group between the centralbulkhead and the opposite side, the transverse bulkheads carryingductsthat are parallel to the bottom and pass through the longitudinalbulkhead, said ducts having both ends open in the sidesof the caisson,said caisson having a row ofhorizontal openings below the top in eachside and in the central bulkhead and another row of hori- V zontalopeningsbelowvthe rst named row in each side and in the centralbulkhead, the openings in both rows being between transverse bulkheads.

v4. A caisson having closed bottom, sides and Aends and anopen top, acentral longitudinal bulkhead extending between the ends, and transversebulkheads extending between rthe |sides and intersecting thelongitudinal bulkhead, said transverse bulkheads and the longitudinalbulk headdviding the interior of the caisson into compartments betweenvsaid longitudinal bulkhead and said sides,

some of said transverse bulkheads being imperforate and having oneormore of the other transverse bulkheads and agroup of vsaidcompartments between them and sealing the compartments of said groupfrom the remaining compartments, the` transverse bulkheads between saidimperfor-ate bulkheads vhaving openings putting all the compertinents ofeach group on one side of the central bulkhead intocommunication withone another, said openings being adjacent a side of the caisson for thecompartments between the central bulkhead and said side, and adjacentthe central bulkhead f or the remainngcompertinents of the group betweenthecentral bulkhead and the opposite side, the transverse bulkheadscarrying ducts that .are-parallel to the bottom and pass through thelongitudinal bulkhead, said ducts having both ends open in the sides ofthe caisson, said caisson having. a row of horizontal openings lbelowthe top in each side and lin the central bulkhead and another row ofhorizontal openings below. the rst named row in each side and in thecentral bulkhead, the openings in both rows beingbetween transversebulkheads, said rows when the caissonistsunk andstands on the earthbeneath a body of waterbeing respectively below the high tide level andlow tide level of said water.

M5, methodof constructing a wharf which consists in building a caissonimposition with both sides there- Qf herizontalad .011e below the,other., and the bottom vertical, creating aternporary hold wit hin` saidy caisson along the lowerside and remote from', t he bottom,. l1ing saidhold to balancethfeweightof the bottom, floating said caisson with saidlower sidesubrnerged, evacuating said hold and weighting thecaisson tov`turn upright withthe bottom lowermost, tioating said caissontothe Shoret line .of a .bedrVy otr/afer.. .and Sinking: it. ,there tillit rests onthe bottom under s aid water, and ballasting and anchoring the caissonto retain it in place:

6, A 2 wharf comprising caissons disposed end to en d atthe. shore.,line of abodyf Water, Said Caissonshavng side s tilted toward saidshore line, rock ballast. iilling said caissons, rocks piled ontheinshoresides of said caisf sons, and a. till of materials betweensaid piledrocks and said shore line, said caissons each having twohorizon1 9 tal rows of openings in the opposite sides, one row below thehigh tide level of the water and the other row below the low tide levelthereof.

7. A wharfcomprising caissons disposed end to end at the shore line of abody of water, said caissons having sides tilted toward said shore line,rock ballast filling said caissons, rocks piled on the inshore sides ofsaid caissons, anda flll of materials between said piled rocks and saidshore line, said caissons each having two horizontal rows of openings inthe opposite sides, one row below the high tide level of the water andthe other row below the low tide level thereof, said caissons eachhaving a projecting ledge from the outer side at the level of the bottomthereof.

References Cited in the le of this patent UNITED STATES PATENTS HadlockFeb. 14, 1905 Hennebique Oct. l5, 1907 Dumais Jan. 7, 1908 Spellman Feb.18, 1919 Williams July 22, 1919 Williams Ang. 17, 1920 Aston Mar. 12,1946 Gerwick Aug. 27, 1954 FOREIGN PATENTS Great Britain 1920 OTHERREFERENCES Eng. News Record, pages 46-48, Ian. 11, 1951, issue.

